1. Field of the Invention
The present invention relates to a microstrip patch antenna device, and more particularly to a frequency tunable microstrip patch antenna device.
2. Description of the Prior Art
The typical microstrip patch antenna devices, as shown in FIGS. 1-8, are provided for attaching onto the objects, particularly the electric facilities, such as the mobile phones, portable phones, etc., and comprise a dielectric intermediate plate 2 disposed between a lower ground board 1 and an upper antenna patch 3, and two feeds 4, 5 disposed in the antenna patch 3 for exciting the antenna patch 3. The operating frequencies of the patch antenna devices are related to or are determined by the areas and/or the shapes and/or the locations of the antenna patches 3. Accordingly, the areas and/or the shapes and/or the locations of the antenna patches 3 are changed or adjusted in order to obtain or to operate the patch antenna devices at different or various frequencies. FIGS. 1-8 illustrate the typical microstrip patch antenna devices that may only change or adjust the antenna patches 3 to different shapes or areas or locations, in order to obtain or to operate the patch antenna devices at different or various frequencies.
However, due to the limit size of the objects, such as the mobile phones, portable phones, etc., the areas of the antenna patches 3 are limited and may not be increased to a area over the allowed attaching or mounting area in the objects. Accordingly, the working frequencies, particularly the obtainable working frequencies of the patch antenna devices are limited. When the areas of the antenna patches are reduced, the signals may not be suitable received, and additional amplifier devices are further required to amplify the receiving signals. In addition, the typical patch antenna devices consume much electricities.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional microstrip patch antennas.
The primary objective of the present invention is to provide a frequency tunable microstrip patch antenna device including one or more capacitors engaged in the antenna patch for increasing or enlarging the effective working area and for increasing the resonant modes of the patch antenna device, or for increasing the effective bandwidth for the patch antenna device.
The other objective of the present invention is to provide a frequency tunable microstrip patch antenna device including one or more fees that may be changed to different positions or locations in the antenna patch for simultaneously exciting different or various kinds of operating modes for the patch antenna device.
The further objective of the present invention is to provide a frequency tunable microstrip patch antenna device that may consume less electric power.
In accordance with one aspect of the invention, there is provided a patch antenna device comprising an antenna patch, and at least one capacitor loaded into the antenna patch for generating and increasing an equivalent working area to the antenna patch. The capacitor may be any kind of suitable capacitor, such as the chip capacitor. The provision of the capacitor into the antenna patch allows the electricity to flow into and to flow out of the capacitor, and consumes less electric power.
A ground board is further. provided, and a dielectric plate is further provided and disposed between the antenna patch and the ground board.
One or more feeds are further provided and loaded into the antenna patch for exciting various kinds of resonate modes or radiation modes at the same time. The feeds may be changed to different positions or locations relative to the antenna patch, for exciting different resonate modes or radiation modes at the same time.
The feeds each includes a probe extended through the dielectric plate and extended toward the ground board. A protective shield is preferably disposed between the probe and the ground board for protecting the probe and for preventing the probe from being grounded by the ground board.